EP1068543B1 - Method for operating several adjacent ultrasonic sensors - Google Patents

Description

The invention relates to a method for operating several neighboring ultrasonic sensors that are synchronized are and of which a first first transmission pulses, a second sends out second transmission pulses and a third third transmission pulse.

A generic method is described in EP 0 519 090 B1. When operating adjacent ultrasonic sensors it may be due to unfavorable reflections from the ultrasound in the environment of the ultrasonic sensors for mutual influence come. The runtime measurement of an ultrasonic sensor is from the echo signal of the neighboring ultrasonic sensor disturbed if the ultrasonic sensors do not transmit synchronously. Then the echo signals may not be able to pass the ultrasonic sensors correctly assigned to the corresponding Have issued transmission pulses. Hence it comes from the runtime evaluation for errors by the switching output is set undefined. So far it has been to solve the problem known to operate the ultrasonic sensors in series, by the supply voltages of the ultrasonic sensors were cyclically switched on or off. The response time of the With this technology, ultrasonic sensors are correspondingly long and is even delayed by internal reset times. Another way to influence each other avoid, so far there has also been compliance with installation regulations, i.e. the specification of minimum distances for the Installation of the ultrasonic sensors. The minimum distances however, are very application-dependent. For many uses this method is excluded if a high level of security is required. Another avoidance solution mutual influence is that the neighboring operated ultrasonic sensors via their release output be connected to each other by a common line and via this a parallel synchronization takes place. in this connection of all proximity switches at the same time Transmitted pulses, so that the problem of the correct timing Assignment of the echo signals to the relevant ultrasonic sensors eliminated. Such parallel synchronization has the disadvantage, however, that the runtime evaluation does not contain structured evaluation algorithms. The EP 0 519 090 B1 describes an interconnection of several Ultrasonic sensors through their release outputs a common line with an automatic parallel or serial synchronization.

However, the sampling of fast events, such as they e.g. required for car counting in the driveways of parking garages is still an unsolved problem.

The invention is therefore based on the object of a method to improve the type mentioned above in that the transit time measurement an ultrasonic sensor of echo signals from neighboring Ultrasonic sensors undisturbed and reliable is possible.

The object is achieved with the features according to claim 1 solved. Then the neighboring ultrasonic sensors synchronized via a common line and transmit pulses handed over alternately at different times. Here is the transmit pulse offset of the individual ultrasonic sensors is essential smaller than the measuring cycle, i.e. than the duration between two consecutive transmit pulses, creating a substantial higher measuring rate can be achieved than e.g. at the known serial synchronization. Due to the changing transmission pulse offset can use the echo signals from neighboring ultrasonic sensors hidden by their constantly changing runtime become.

To achieve this, the process is advantageous with the Features developed according to claim 2. After that, from echo signals of several measuring cycles received by the ultrasonic sensors, i.e. both your own echo signals and external echo signals, compared in terms of their location and evaluated.

As a particularly advantageous development of the method proved if as a stability criterion for the determination the wanted echo signal of each ultrasonic sensor in successive measuring cycles always within the same time window occurring position of a single echo signal serves. The time window is in terms of size and position based on the previous transmission pulse. Just the own echo signal always keeps its position approximately at, while changing from measuring cycle to measuring cycle Transmit pulse offset changes the position of the external echo signals. This is a simple and at the same time secure criterion given to determine the echo signal sought.

An embodiment of the invention is as follows explained in more detail using a drawing.

The method according to the invention for direction-independent counting vehicles using several neighboring ultrasonic sensors assumes that the Ultrasonic sensors are operated synchronized, e.g. in in the manner described in EP 0 519 090 B1. For this are the ultrasonic sensors are connected to each other by a line. The synchronization pulses of the ultrasonic sensors at least partially overlap in time, and on the There is a ground potential as long as there is any Synchronizing pulse from the ultrasonic sensors is present. Only when the line assumes the potential HIGH is that Willingness to emit new ultrasonic waves, i.e. given a transmission pulse of the proximity switch. This through the synchronization pulses of the ultrasonic sensors conditional edge changes result in a clock signal, its positive edges as reference times for the transmission pulses the ultrasonic sensors. The Transmitting impulses alternating with respect to the positive ones Flanks issued offset. The transmission pulse offset of the individual Ultrasonic sensors is much smaller than that Measuring cycle, i.e. than the duration between two consecutive Transmitting pulses from an ultrasonic sensor. hereby a much higher measuring rate can be achieved than e.g. in the serial synchronization mentioned at the beginning. The higher measuring rate is all the more important if with the Ultrasonic sensors detect fast moving objects should be. Due to the changing transmission pulse offset the echo signals from the neighboring ultrasonic sensors due to their constantly changing term in relation to the Transmission pulse of the ultrasound sensor under consideration is hidden become. The ultrasonic sensors save in one Measuring cycle the running time of the own echo signal and the running times of the neighboring ultrasonic sensors. The Runtimes of the echo signals of three measuring cycles are combined compared, only the duration of the own echo signals the specified stability criterion of the ultrasonic sensor Fulfills. This is true if the echo signal is at least found three times in a row in the same time window becomes. The location of the time window can vary from the measuring section, e.g. between the ultrasonic sensor and the floor or the ultrasonic sensor and one Roof area of a vehicle, move. The size of this Time window can be adapted to the respective application be specified.

Using an example with three synchronized ultrasonic sensors become the waveforms that occur during operation explained according to the figure. The top waveform A shows this is due to the synchronization pulses of the individual ultrasonic sensors automatically formed clock signal, as detailed can be found in EP 0 519 090 B1. As before mentioned above, starting from the positive edges of the Clock signal with changing transmission pulse offset the transmission pulses of the ultrasonic sensors.

The transmission pulses S1 shown in track B for the ultrasonic sensor have for the measuring clocks M1, M2 and M3 of Clock signal three different transmission pulse offsets d1, d2 and d3, in the present example d1 = 0 ms, d2 = 5 ms and d3 = 10 ms. These occur in the order mentioned and then repeat themselves cyclically.

The tracks D and F below show the position of the transmission pulses S2 for the second ultrasonic sensor and S3 for the third ultrasonic sensor. The transmission pulses S2 have started with measuring cycle 1, the following sequence of the transmission pulse offsets, namely d2 for measuring cycle M1, d3 for measuring cycle M2 and d1 for measuring cycle M3 with a subsequent cyclical one Repetition. The transmission pulses S3 from the third ultrasonic sensor start with the transmission pulse offset d3 at Measuring clock M1, which is the transmission pulse offset d1 for measuring clock M2 and then connect d2 for measuring cycle M3. Have along d1, d2 and d3 in the present example always the above Numerical values. The transmission pulses of the respective ultrasonic sensor are assigned in tracks C, E, G those of the relevant ultrasonic sensor received echo signals recorded. The first ultrasonic sensor receives in measuring cycle 1 after about 15 ms its own echo signal E1 and after another 5 or 10 ms due to the transmission pulse offset Echo signals E2 or E3 of the second or third ultrasonic sensor. In the subsequent measuring cycle M2, your own occurs Echo signal E1 after 15 ms of the transmission pulse S1. by virtue of of the transmission pulse offset occurs the echo signal E3 5 ms before the echo signal E1 and the echo signal E2 5 ms later. In the subsequent measuring cycle 3 results from the Transmit pulse offset another different order of Echo signals with the first received echo signal E2, the after 5 ms following echo signal E3 and after another 5 ms following echo signal E1. You can see that only the echo signal E1 meets the stability criterion and three times in a row in the same time window, namely after 15 ms, occurs. This time window is in the present example, adapted to the transmission pulse offset, less than 5 ms.

The temporal transmission pulse offset must be chosen so large that the echo signals can be detected selectively. If that Echo signal at least three times in succession in the named Time slot is determined, the transmitter output of the Ultrasonic sensor its state and it becomes a count given.

As already mentioned above, the location of the echo signals and the associated time windows in which the echo signals are located, on the respective measuring section.

Unter der Adresse 1 für den ersten Ultraschall-Sensor d1 = 0 ms, d2 = 5 ms, d3 = 10 ms, d1 = 0 ms, d2 = 5 ms, d3 = 10 ms usw.,

unter der Adresse 2 für den zweiten Ultraschall-Sensor d2 = 5 ms, d3 = 10 ms, d1 = 0 ms, d2 = 5 ms, d3 = 10 ms, d1 = 0 ms usw. und

unter der Adresse 3 für den dritten Ultraschall-Sensor d3 = 10 ms, d1 = 0 ms, d2 = 5 ms, d3 = 10 ms, d1 = 0 ms, d2 = 5 ms usw..

The echo signals E2 and E3 of the second and third ultrasound sensors according to tracks D and F are also compared and evaluated in a corresponding manner in order to filter out only the transit times of the own echo signals in the manner described, ie the echo signals from adjacent ultrasound sensors. Hide sensors. The transmit pulse offsets for the various ultrasonic sensors can be stored under the addresses assigned to them. The following assignment is possible, for example:

At address 1 for the first ultrasonic sensor d1 = 0 ms, d2 = 5 ms, d3 = 10 ms, d1 = 0 ms, d2 = 5 ms, d3 = 10 ms etc.,

at address 2 for the second ultrasonic sensor d2 = 5 ms, d3 = 10 ms, d1 = 0 ms, d2 = 5 ms, d3 = 10 ms, d1 = 0 ms etc. and

at address 3 for the third ultrasonic sensor d3 = 10 ms, d1 = 0 ms, d2 = 5 ms, d3 = 10 ms, d1 = 0 ms, d2 = 5 ms etc.

The ultrasonic sensors work in the described method independent, i.e. without additional control effort. It goes without saying that the ultrasound sensors are controlled centrally possible.

Claims (3)

1. Method for operating a plurality of adjacent ultrasound sensors which are synchronised and in which a first ultrasonic sensor emits first transmission pulses (S1), a second ultrasonic sensor emits second transmission pulses (S2), and a third ultrasonic sensor emits third transmission pulses (S3), characterised in that a clock signal is generated with at least a first (M1), a second (M2) and a third measurement clock (M3), which occur in sequence, that a first one of the first transmission pulses (S1) is generated with a first transmission pulse offset (d1) for the first measurement clock (M1), a second one of the first transmission pulses (S1) is generated with a second transmission pulse offset (d2) for the second measurement clock (M2), and a third one of the first transmission pulses (S1) is generated with a third transmission pulse offset (d3) for the third measurement clock (M3), corresponding to a first transmission pulse sequence d1-d2-d3 for the first transmission pulses (S1) for the measurement clocks (M1, M2, M3), that a first one, a second one and a third one of the second transmission pulses (S2) are generated for the first (M1), the second (M2) and the third measurement clock (M3) with the second (d2), the third (d3) and the first transmission pulse offset (d1) according to a second transmission pulse sequence d2-d3-d1, and that a first one, a second one and a third one of the third transmission pulses (S3) are generated for the first (M1), the second (M2) and the third measurement clock (M3) with the third (d3), the first (d1) and the second transmission pulse offset (d2) according to a third transmission pulse sequence d3-d1-d2.
2. Method for operating a plurality of adjacent ultrasonic sensors according to Claim 1, characterised in that the first, second and third echo signals (E1, E2 and E3) are assigned to the first, second and third transmission pulses (S1, S2 and S3) respectively and the echo signals (E1, E2, E3) of a plurality of measurement cycles received by the first, second and third ultrasonic sensor respectively are compared with each other and evaluated with respect to their position.
3. Method for operating a plurality of adjacent ultrasonic sensors according to Claim 2, characterised in that the position of a single echo signal (E1, E2, E3) is used as a stability criterion to determine each ultrasonic sensor's sought echo signal (E1, E2 or E3 respectively). In successive measurement cycles the position of the single echo signal (E1, E2, E3) always occurs within the same time window, which with respect to size and position is equal to the transmission pulse (S1, S2 or S3) which precedes it.

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